The present invention relates to improvements in venetian blinds in general, and more particularly to improvements in venetian blinds of the type having horizontal slats and means for turning the slats between open and closed positions. Still more particularly, the invention relates to improvements in venetian blinds wherein the means for turning the slats has parts which are mounted at a level above the uppermost slat and are designed to move the slats to open positions in response to shortening of the blind.
In presently known venetian blinds of the just outlined character, the slats assume open or nearly open positions (in which each slat is located in a substantially horizontal plane) in automatic response to raising of the slats, and the slats assume closed or practically closed positions in automatic response to lowering of the slats. Such venetian blinds exhibit the advantage that the slats allow more light to pass through the blind during raising, i.e., at a time when the occupant of the room normally desires to admit more light (e.g., in the evening when the admission of additional light is desirable in view of the progressing darkness at the outside). However, the movement of slats to closed positions in automatic response to lengthening of the venetian blind constitutes a drawback, at least in many instances, because a complete lowering of slats invariably entails a complete or substantial darkening of the room. For example, a housewife is likely to cause all venetian blinds in a room to assume their fully or partly extended positions when the windows are closed; however, such extension of all blinds is not intended to prevent entry of daylight but merely to enhance the appearance of the room.